BEHAVIOR AND FAILURE ANALYSIS OF A MULTIPLE-FRAME HIGHWAY BRIDGE IN THE 1994 NORTHRIDGE EARTHQUAKE

Abstract

This study examines the partial collapse and failure of the Route 14/Interstate 5 Separation and Overhead bridge, a curved ten-span concrete structure, during the 1994 earthquake in Northridge California. It examines the cause of the failure by comparing estimates of the capacities and demands of components in the bridge. Nonlinear static analysis, also known as pushover analysis, is used to determine the capacity of a frame In order to evaluate the earthquake response, nonlinear dynamic analysis results are used. The demand capacity comparison indicates that the most likely cause of the collapse was due to the shear failure of two piers in a brittle- ductile mode. A three-dimensional model of the bridge is used to investigate the behavior of the bridge had it been seismically retrofit before the earthquake. The displacements from the nonlinear model are compared with linear models. It is shown that the linear compression provides a good estimate of the displacement demands.